*{
    margin: 0;
    padding: 0;
}
li {
  list-style: none;
}
.box1{
     position: relative;
     top: 100px;
     left: 100px;
     width: 200px;
     height: 200px;
     background-color: aqua;
}
.box2{
    width: 200px;
    height: 200px;
    background-color: #00ff00;
}
.son{
    position: absolute;
    bottom: 200px;
    right: 100px;
    width: 200px;
    height: 200px;
    background-color: #2600ff;  
}
.father{
    width: 500px;
    height: 500px;
    background-color: #ff80ff;
}
.Grandfather{
    position: relative;
    width: 600px;
    height: 600px;
    background-color: #ff8000;
    margin:50px;
}
.hangxing{
    position: fixed;
    top: 100px;
    left: 40px;
}
.fixed{
    position: fixed;
    /* 1、走浏览器宽度的一半 */
    left: 50%;
    /*2、 利用margin 走版心盒子宽度一半距离 */
    margin-left: 405px;
    width: 50px;
    height: 150px;
    background-color: #ff8000;
}
.w{
    width: 800px;
    height: 1400px;
    background-color: #ff80ff;
    margin: 0 auto;
}
.nav{
    /* 粘性定位 */
    position:sticky;
    width: 800px;
    height: 50px;
    background-color: #ff80ff;
    margin: 100px auto;
}
.box{
    position: absolute;
     /* 如何给绝对定位水平垂直居中  */
    /* 1.left 走50% */
    left: 50%;
    /* 2.margin 负值 往左边走 自己盒子宽度的一半 */
    margin-left: -100px;
    top: 50%;
    margin-top: -100px;
    width: 200px;
    height: 200px;
    background-color: #2600ff;
    /* margin: auto; */
}
.tb-promo {
    position: relative;
    width: 520px;
    height: 280px;
    background-color: aqua;
    margin: 100px auto;
}
.tb-promo img {
    width: 520px;
    height: 280px;
}
/* 并集选择器可以集体声明相同的样式 */
.prev, .next{
    position: absolute;
    top: 50%;
   /* 盒子高度一半 */
    margin-top: -15px;
    width: 20px;
    height: 30px;
    color: #fff;
    text-align: center;
    text-decoration: none;
    line-height: 30px;
    background: rgba(0, 0, 0, 0.3);
}
.prev { 
   left: 0;
   border-top-right-radius: 15px;
   border-bottom-right-radius:15px 
}
.next {
  right: 0;
  border-top-left-radius: 15px;
  border-bottom-left-radius:15px 
}
.prome-nav{
    position: absolute;
    left: 50%;
    margin-left: -35px;
    bottom: 15px;
    width: 70px;
    height: 13px;
    background: rgba(0, 0, 0, 0.3);
    border-radius: 7px;
}
.prome-nav li {
    float: left;
    width: 8px;
    height: 8px;
    background-color: #fff;
    border-radius: 50%;
    margin: 3px;
}
/* 不要忘记选择器权重问题 */
.prome-nav .selected{
    background-color: #ff5000;
}
